Design and first result of combined Langmuir-magnetic probe on J-TEXT tokamak

2021 ◽  
Author(s):  
Qinghu Yang ◽  
Zhipeng Chen ◽  
Zhigang Hao ◽  
Yangming Zhao ◽  
Xin Xu ◽  
...  
Keyword(s):  
Eddy Current ◽  
Magnetic Surface ◽  
Mutual Inductance ◽  
Magnetic Probe ◽  
Shielding Effect ◽  
Magnetic Fluctuations ◽  
Electromagnetic Mode ◽  
Pneumatic Device ◽  
Magnetic Fluctuation ◽  
Electromagnetic Signals

Abstract In order to measure boundary electrostatic and magnetic fluctuations simultaneously, a set of combined Langmuir-magnetic probe (CLMP) has been designed and built on Joint-Texas Experimental Tokamak (J-TEXT). The probe consists of 8 graphite probe pins and a 3D magnetic probe, driven by a mechanical pneumatic device. By means of simulation, the shielding effect of the graphite sleeve on the magnetic fluctuation signal is explored, and the influence of the eddy current was reduced by cutting the graphite sleeve. In the experiment, it has been verified that the mutual inductance of electromagnetic signals can be ignored. And a 70~90kHz electromagnetic mode is observed around the last closed magnetic surface (LCFS). The establishment of CLMP provides data for the exploration of the coupling of electrostatic and magnetic fluctuations.

scholarly journals Analysis of AC Transport Loss in Conductor on Round Core Cables

2021 ◽  
Author(s):  
Jiabin Yang ◽  
Chao Li ◽  
Mengyuan Tian ◽  
Shuyu Liu ◽  
Boyang Shen ◽  
...  
Keyword(s):  
Eddy Current ◽  
Complex Geometry ◽  
Layer Structure ◽  
Single Layer ◽  
Element Model ◽  
Structure Design ◽  
Ac Loss ◽  
Shielding Effect ◽  
Transport Loss ◽  
Electro Magnetic

AbstractThe conductor on round core (CORC) cable wound with second-generation high-temperature superconducting (HTS) tapes is a promising cable candidate with superiority in current capacity and mechanical strength. The composing superconductors and the former are tightly assembled, resulting in a strong electro-magnetic interaction between them. Correspondingly, the AC loss is influenced by the cable structure. In this paper, a 3D finite-element model of the CORC cable is first built, and it includes the complex geometry, the angular dependence of critical current and the periodic settings. The modelling is verified by the measurements conducted for the transport loss of a two-layer CORC cable. Subsequently, the simulated results show that the primary transport loss shifts from the former to the superconductors as the current increases. Meanwhile, the loss exhibited in the outer layer is larger than that of the inner layer, which is caused by the shielding effect among layers and the former. This also leads to the current inhomogeneity in CORC cables. In contrast with the two-layer case, the simulated single-layer structure indicates stronger frequency dependence because the eddy current loss in the copper former is always dominant without the cancellation of the opposite-wound layers. The core eddy current of the single structure is denser on the outer surface. Finally, the AC transport losses among a straight HTS tape, a two-layer cable and a single-layer cable are compared. The two-layer structure is confirmed to minimise the loss, meaning an even-numbered arrangement makes better use of the cable space and superconducting materials. Having illustrated the electro-magnetic behaviour inside the CORC cable, this work is an essential reference for the structure design of CORC cables.

scholarly journals Conductivity Classification of Non-Magnetic Tilting Metals by Eddy Current Sensors

Sensors ◽  
2020 ◽  
Vol 20 (9) ◽  
pp. 2608 ◽  
Author(s):  
Yue Du ◽  
Zhijie Zhang ◽  
Wuliang Yin ◽  
Shuang Zhu ◽  
Ziqi Chen ◽  
...  
Keyword(s):  
Eddy Current ◽  
Convenient Method ◽  
Mutual Inductance ◽  
Classification Algorithm ◽  
Phase Compensation ◽  
Classification Rate ◽  
Industrial Economy ◽  
Waste Classification ◽  
Resource Reuse

Metallic waste classification benefits the environment, resource reuse and industrial economy. This paper provides a fast, non-contact and convenient method based on eddy current to classify metals. The characteristic phase to characterize different conductivity is introduced and extracted from mutual inductance in the form of amplitude and phase. This characteristic phase could offer great separation for non-tilting metals. Although it is hard to classify tilting metals by only using the characteristic phase, we propose the technique of phase compensation utilizing photoelectric sensors to obtain the rectified phase corresponding to the non-tilting situation. Finally, we construct a classification algorithm involving phase compensation. By conducting a test, a 95 % classification rate is achieved.

scholarly journals A multichannel magnetic probe system for analysing magnetic fluctuations in helical axis plasmas

2013 ◽  
Vol 84 (9) ◽  
pp. 093501 ◽  
Author(s):  
S. R. Haskey ◽  
B. D. Blackwell ◽  
B. Seiwald ◽  
M. J. Hole ◽  
D. G. Pretty ◽  
...  
Keyword(s):  
Magnetic Probe ◽  
Helical Axis ◽  
Magnetic Fluctuations ◽  
Probe System

Measurement of Wall Thinning through Insulation with Ferromagnetic Cladding Using Pulsed Eddy Current Testing

2011 ◽  
Vol 301-303 ◽  
pp. 426-429
Author(s):  
Zhi Yuan Xu ◽  
Xin Jun Wu ◽  
Chen Huang ◽  
Yi Hua Kang
Keyword(s):  
Eddy Current ◽  
Steel Plate ◽  
Thickness Measurement ◽  
Measurement Range ◽  
Galvanized Steel ◽  
Shielding Effect ◽  
Pulsed Eddy Current ◽  
Wall Thinning ◽  
The Common ◽  
Lift Off

Pulsed eddy current (PEC) technique has been successfully used for measuring wall thinning of carbon steel equipments without removal of the insulation. In field applications, the probe performance decreases in presence of ferromagnetic claddings. This paper presents a method based on saturation magnetization to solve this problem. The main principle of this method is to weaken the magnetic shielding effect of the cladding by magnetizing it to saturation. A U-shaped magnetizer is designed to realize this method. Contrast experiments are performed on a Q235 steel plate covered by a galvanized steel cladding. The experiment results show that the thickness measurement range and lift-off range are increased by applying this method to the common PEC probe.

scholarly journals Statistical analysis of severe magnetic fluctuations in the near-Earth plasma sheet observed by THEMIS-E

2017 ◽  
Vol 35 (5) ◽  
pp. 1131-1142 ◽  
Author(s):  
Heqiucen Xu ◽  
Kazuo Shiokawa ◽  
Dennis Frühauff
Keyword(s):  
Magnetic Field ◽  
Plasma Sheet ◽  
High Speed ◽  
Sampling Rate ◽  
Time History ◽  
Time Interval ◽  
Magnetic Fluctuations ◽  
Current Disruption ◽  
Magnetic Fluctuation ◽  
Inside Out

Abstract. We statistically analyzed severe magnetic fluctuations in the nightside near-Earth plasma sheet at 6–12 RE (Earth radii; 1 RE = 6371 km), because they are important for non-magnetohydrodynamics (non-MHD) effects in the magnetotail and are considered to be necessary for current disruption in the inside-out substorm model. We used magnetic field data from 2013 and 2014 obtained by the Time History of Events and Macroscale Interactions during Substorms E (THEMIS-E) satellite (sampling rate: 4 Hz). A total of 1283 severe magnetic fluctuation events were identified that satisfied the criteria σB∕B > 0. 5, where σB and B are the standard deviation and the average value of magnetic field intensity during the time interval of the local proton gyroperiod, respectively. We found that the occurrence rates of severe fluctuation events are 0.00118, 0.00899, and 0.0238 % at 6–8, 8–10, and 10–12 RE, respectively, and most events last for no more than 15 s. From these occurrence rates, we estimated the possible scale sizes of current disruption by severe magnetic fluctuations as 3.83 RE3 by assuming that four substorms with 5 min intervals of current disruption occur every day. The fluctuation events occurred most frequently at the ZGSM (Z distance in the geocentric solar magnetospheric coordinate system) close to the model neutral sheet within 0.2 RE. Most events occur in association with sudden decreases in the auroral electrojet lower (AL) index and magnetic field dipolarization, indicating that they are related to substorms. Sixty-two percent of magnetic fluctuation events were accompanied by ion flow with velocity V > 100 km s−1, indicating that the violation of ion gyromotion tends to occur during high-speed flow in the near-Earth plasma sheet. The superposed epoch analysis also indicated that the flow speed increases before the severe magnetic fluctuations. We discuss how both the inside-out and outside-in substorm models can explain this increase in flow speeds before magnetic fluctuation events.

Design and optimisation of mutual inductance based pulsed eddy current probe

Measurement ◽  
2019 ◽  
Vol 144 ◽  
pp. 402-409 ◽  
Author(s):  
Denis Ijike Ona ◽  
Gui Yun Tian ◽  
Ruslee Sutthaweekul ◽  
Syed Mohsen Naqvi
Keyword(s):  
Eddy Current ◽  
Mutual Inductance ◽  
Pulsed Eddy Current
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